In present commercial undercarpet wiring systems, a main five conductor flat cable generally extends upon a floor from a discrete wired three-phase feeder into the area to be served with power. Taps are made to the main cable by connecting thereto three or four conductor flat secondary cables. A three conductor cable can tap any one of the three phases of the five conductor cable. The four conductor cables tap off two phase power and each phase thereof may in turn be tapped off by connection of further three conductor secondary cables to the four conductor cable.
In the commercial wiring system introduced by the assignee hereof, the secondary cables are placed in overlapping relation to the main cable. Connections are made between conductors of the cables being interconnected by making a perforation through such conductors, inserting an insulation-piercing connector therein and crimping same onto each of the cables to pierce the insulation thereof and electrically engage the respective conductors.
As is set forth in detail in U.S. Pat. No. Re. 31,336 and U.S. Pat. No. 4,315,662, both commonly assigned herewith, such overlapping system is effectively installed by providing assistance to the installer as respects the selection of connections to be made. Referring to FIG. 4 of U.S. Pat. No. Re. 31,336, when one applies a four conductor cable atop a five conductor cable, twenty zones of registration exist as between the nine individual conductors at hand. Improper zone selection possibilities abound, absent guidance to an installer.
Such guidance is presented by method in U.S. Pat. No. Re. 31,336 whereby, upon selection of an origin zone for connection, the method precludes from connection use all other connection zones in registry with the neutral conductors present at the origin zone. This practice is repeated for the ground conductors of the cables, which separate the neutral conductors from the active phase conductors. Following this step, the method provides for selection plural zones in registry with individual conductors among remaining conductors, while precluding from connection use other zones in registry with such conductors, as will be understood further by reference to the U.S. Pat. No. Re. 31,336. The method leads to a connection pattern wherein connection zones in limited number are made accessible and indication is provided for selective use of such accessible zones. A template for use in practicing this method is shown in both the U.S. Pat. No. Re. 31,336 and U.S. Pat. No. 4,315,662, both of which are incorporated herein by this reference thereto.
While fully effective for implementing the described method, the template referred to has certain practical shortcomings. Since the template is used also for aligning the cables in mutually orthogonal relation in the case of a tap, and in aligned relation in the case of a splice, the template is present in the course of installation, cable run by cable run, and includes a plate assembly for disposition beneath the cables for receiving and aligning same. This gives rise to both expense and bulkiness of the template tool and increased installation time. Further, since the template implements the step of precluding access to unused connection zones in its preferred embodiment by blocking access thereto through the intervening presence of physical matter over such zones, it is relatively heavy and not readily handled.